Xen lack of preemption in evtchn_reset() / evtchn_destroy() DoS (XSA-344)

medium Nessus Plugin ID 144857


The remote Xen hypervisor installation is missing a security update.


A denial of service (DoS) vulnerability exists in Xen servers in FIFO event channel modules evtchn_reset() / evtchn_destroy() due to a lack of preemption. An authenticated, local attacker can mount a Denial of Service (DoS) attack affecting the entire system.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.


Apply the appropriate patch or workaround according to the vendor advisory.

See Also


Plugin Details

Severity: Medium

ID: 144857

File Name: xen_server_XSA-344.nasl

Version: 1.3

Type: local

Family: Misc.

Published: 1/12/2021

Updated: 6/3/2021

Configuration: Enable paranoid mode

Risk Information

CVSS Score Source: CVE-2020-25601


Risk Factor: Medium

Score: 4.4


Risk Factor: Medium

Base Score: 4.9

Temporal Score: 3.6

Vector: AV:L/AC:L/Au:N/C:N/I:N/A:C

Temporal Vector: E:U/RL:OF/RC:C


Risk Factor: Medium

Base Score: 5.5

Temporal Score: 4.8

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Temporal Vector: E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:xen:xen

Required KB Items: installed_sw/Xen Hypervisor, Settings/ParanoidReport

Exploit Ease: No known exploits are available

Patch Publication Date: 9/22/2020

Vulnerability Publication Date: 9/22/2020

Reference Information

CVE: CVE-2020-25601

IAVB: 2020-B-0056-S

CWE: 400